There are two types of problems that prevent hotkeys from workingon many of the machines supported by toshiba_acpi. The first ofthese is the lack of a functioning SCI for hotkey events. For thesemachines it is possible to filter the Fn keypresses from thekeyboard and generate a notification by executing the ACPI NTFYmethod.

The second problem is a lack of support for HCI_SYSTEM_EVENT, whichis used for reading the hotkey scancodes. On these machines thescancodes can be read by executing the ACPI NTFY method.

This patch fixes both problems by installing an i8042 filter whenthe NTFY method is present to generate notifications and bydetecting which of INFO or HCI_SYSTEM_EVENT is supported forreading scancodes. If neither method of reading scancodes issupported, the hotkey input device is not registered.